Andy,
Perhaps I can help here. I was an AEO with 820 Sqn from 81 to 83, and served with HRH almost all of that time. I went down to the Falklands, and was part of a two aircraft detachment that went ashore into San Carlos from just before the surrender until just afterwards. HRH was part of that detachment, which was commanded by our Senior Pilot, Lt Cdr Keith Dudley.
Yes, that is 'H' - and he's in an SK2. I assume it's an 825 Sqn cab, but can't confirm that. It's certainly not an 820 machine.
I believe that some of our crews did fly with 825 while we were ashore at San Carlos, and 'H' would certainly have taken his turn.
Hope this helps
Engines